1. Field of the Invention
The present invention relates to a new process for the preparation of nitromethylene derivatives which have insecticidal properties.
2. Background Information
It has already been disclosed that nitromethylene derivatives of the formula (I) ##STR3## in which R represents hydrogen or lower alkyl,
m represents the numbers 2, 3 or 4, and PA1 n represents the numbers 0, 1, 2 or 3, PA1 m represents numbers 2, 3 or 4, and PA1 n represents numbers 0, 1, 2 or 3, PA1 X.sup.1 and X.sup.2, independently of one another, represent fluorine or chlorine, PA1 Y represents halogen or the --OSO.sub.2 Y' group, where PA1 Y' represents lower alkyl or represents aryl, with diamines of the formula (VI) EQU H.sub.2 N--(CH.sub.2).sub.m --NH.sub.2 (VI) PA1 in which PA1 m has the abovementioned meaning.
are obtained when compounds of the formula (II), ##STR4## in which R, m and n have the abovementioned meanings, are reacted with compounds of the formula (III), ##STR5## in which R.sup.1 represents lower alkyl or benzyl, or both R.sup.2 groups together represent an alkylene group having at least 2 carbon atoms,
in the presence of an inert organic solvent, such as, for example, an alcohol or ether, at temperatures between 0.degree. C. and 100.degree. C. (cf. European Published Specification No. 163,855).
However, the disadvantage in this process is that the starting materials of the formula (III) must be prepared from nitromethane and carbon disulphide (cf. Chem. Berichte, 100, p. 591 [1967]).
Nitromethane is a generally known explosive having a high shock sensitivity. Carbon disulphide has a very low flashpoint of -20.degree. C. and a relatively low ignition temperature of +120.degree. C. Industrial use of these two starting materials would necessitate extensive and costly safety measures, for which reason the industrial value of this process is very limited.
A further disadvantage of the process is the cleavage of strongly smelling mercaptans during the reaction of the compounds of the formula (II) with those of the formula (III).
The reaction of 1-aminoalkanethiols with 2,2,2-trihalogeno-1-nitroethane derivatives to produce nitromethylene group-containing 1,3-thiazolidines, 1,3-thiazines and 1,3-thiazepines is known. In this connection see European Patent Specification No. 0,135,803 A2. However, 1-aminoalkanethiols which are significantly more reactive than the diamines were employed in this reaction.